Warfarin tablets
Use of antithrombotic drugs is associated with a higher risk of subdural hematoma, according to a case-control study of more than 400,000 individuals in Denmark.
The highest risk of subdural hematoma was observed in patients who were taking both a vitamin K antagonist (VKA) and clopidogrel.
The study also showed that the incidence of subdural hematoma increased from 2000 to 2015, which appeared to be associated with the increased use of antithrombotic drugs over that time period.
David Gaist, MD, PhD, of Odense University Hospital and the University of Southern Denmark, and his colleagues conducted this research and reported the results in JAMA.
The researchers evaluated 10,010 patients, ages 20 to 89, with a first-ever subdural hematoma diagnosis from 2000 to 2015. The patients were matched to 400,380 individuals from the general population.
Among the patients with subdural hematoma (average age, 69), 47% were taking antithrombotic medications.
The researchers used conditional logistic regression models to estimate the association between antithrombotic drugs and subdural hematoma risk, adjusting for a range of factors. With the following data, they adjusted for age, sex, calendar period, comorbidity, education level, and income level.
The team found that current low-dose aspirin use was associated with a low risk of subdural hematoma (adjusted odds ratio [OR]=1.24).
Current clopidogrel (OR=1.80) and direct oral anticoagulant (OR=1.55) use were both associated with a moderate risk.
And current VKA use was associated with the highest risk of all the agents when given alone (OR=3.69).
Concurrent use of more than one antithrombotic drug was also associated with a high subdural hematoma risk:
- Low-dose aspirin and clopidogrel (OR=2.45)
- Low-dose aspirin and direct oral anticoagulant (OR=2.52)
- Low-dose aspirin and VKA (OR=4.00)
- Clopidogrel and VKA (OR=7.93).
There was one exception to this. Low-dose aspirin combined with the antiplatelet drug dipyridamole was associated with a risk similar to that of low-dose aspirin alone (OR=1.17).
The researchers noted that the prevalence of antithrombotic drug use increased in the general population over the time period studied, from 31.0 per 1000 individuals in 2000 to 76.9 per 1000 individuals in 2015 (P<0.001 for trend).
The overall subdural hematoma incidence rate increased as well, from 10.9 per 100,000 person-years in 2000 to 19.0 per 100,000 person-years in 2015 (P<0.001 for trend).
The largest increase in subdural hematoma incidence was among patients older than 75 years of age—from 55.1 per 100,000 person-years to 99.7 per 100,000 person-years (P<0.001 for trend).
